Performance maintenance of electromagnetic vibrating feeder
1. Error analysis
The weighing of raw materials is the central part of the batching work. In order to ensure the accuracy of weighing, the weighing error must be strictly controlled. Generally speaking, weighing errors can be divided into three types: systematic errors, accidental errors and gross errors. The factor of system error is relatively fixed, and the value is often unchanged, so it is also called constant error, which can be eliminated after correction; accidental error is not easy to control, but after statistical analysis, it conforms to the law of mathematical statistics: negligent error is caused by improper operation Or due to instrument failure, the value changes impermanently and does not have a certain pattern.
Electronic automatic scales are widely used in weighing equipment in glass factories. It has simple structure, small size, light weight, automatic weighing and remote control, and weighing accuracy is much higher than that of ordinary weighing instruments. However, in the automatic batching system, the electronic scale is generally used in combination with the vibrating feeder. The loading and unloading of the electronic scale is realized by the feeder, and the sensitivity of the feeder directly affects the weighing. Accuracy, it should be noted that the numerical error in this case is the feeding error of the vibrating feeder and has nothing to do with the electronic scale itself.
In order to improve the feeding accuracy of the feeder, a variety of weighing methods can be used, such as emptying method, cumulative weighing method, residual method, etc. When feeding or discharging the feeder, use two speed control: set When determining the weighing value, consider the drop value during the feeding process; when a large feeding error occurs, as a remedial measure, you can set the “small two in one” program to automatically correct it. Nevertheless, it is still more important to ensure that the feeder is always in a stable state.
2.1 Mechanical index K
The mechanical index K is expressed by the ratio of the acceleration of the feed trough to the acceleration of gravity.
Where f: power frequency
π: Amplitude of feeding trough
g: acceleration of gravity
2.2 Power frequency f
When the driving angle is constant, the feeding capacity depends on the product of frequency and amplitude. After one of them is reduced, the other should be increased.
2.3 Amplitude a
The feeding capacity of the feeder is proportional to the amplitude, so increasing the amplitude can increase the feeding capacity, but this will destroy the particles of the material, so the amplitude is generally controlled at 0.5-1.5 mm.
2.4 Drive angle p
For the mechanical index K of the electromagnetic vibrating feeder, there is a corresponding driving angle p, as shown in Figure 2, the currently selected value is mostly 20-25°.
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